The current bar plots work somewhat, but it's not easy to add new features to them. The bar plot module should be refactored to accomodate several new desired features. This issue unifies #24, #260, and #277. After this module is complete, it can probably be modified slightly to support box plots too (#244) to make it easier to display grouped box plots. Perhaps a single class can be used for bar and box plots.

Example (from matplotlib)

• This graph has 5 groups (G1, G2, G3, G4, and G5)
• This graph has 2 bar series (Men and Women)

One can say that if several bar series objects have the same number of elements in them, it is possible to display them organized by group. Each bar series and each group has its own label.

Features:

• can display a single bar series
• can display several bar series arranged by groups
• each bar series can be individually customized
• each bar series should appear separately in the legend
• it should be easy to display as vertical or horizontal bars
• it should be possible to display as stacked bars
• optional error-bars should be supported
• add option to customize lines
• add option to display values over bars
• add support for box plots
• display scatter data next to plots
• display data distribution curve